Attempts have been made in the prior art to provide an emergency braking system for automotive vehicles equipped with air brakes, which will serve to prevent the runaway of such vehicles should the vehicle service braking system fail due to faulty brake mechanisms, breakage in the fluid power lines, or for some other reason. Most prior art air brake emergency braking systems, however, are subject to certain disadvantages in that, for instance, they are too bulky, or in some cases consist of too many parts. In other instances, considerable and expensive changes on the truck or trailer chassis are necessary to install the prior art emergency braking systems. Moreover, some of the prior art emergency braking mechanisms are too expensive to justify their installation.
Many of the prior art emergency braking mechanisms are merely auxiliary brakes which can be applied in case the service brakes malfunction. In other words, such prior art mechanisms do not operate automatically should the service brakes become ineffective, and there is no means to inform the operator of a vehicle in advance that the service brakes are not working. Still other prior art mechanisms act on the cam shaft lever of the service brakes and cannot be applied in emergencies when the brakes are out of adjustment.
Some of the prior art emergency braking systems can also be used for parking purposes. However, for the most part, such prior art brakes can only be released by compressed air from the truck. Therefore, if such a prior art brake was installed in a trailer, there would be no way of moving the trailer unless a source of compressed air was available. The braking mechanism of the present invention has the feature in that it can be released and re-set mechanically and without the need for compressed air.
The present invention provides a relatively simple and inexpensive brake system which can be incorporated into trailers, tractors, trucks or buses, and which can be easily installed in existing vehicles equipped with air brakes. The invention also provides a brake which is economical and efficient, and which rapidly and automatically latches the air brakes of the vehicle whenever a failure in the service brake power system occurs, for any reason. Moreover, the invention provides a brake system which can be used for parking purposes, and which can be easily set and released mechanically.
Most heavy trucks and trailers are equipped with air brakes in which necessary pressure is built up and maintained in a storage tank by a compressor. Actuation of the brakes releases air under pressure against a diaphragm in a brake chamber, which is operatively connected to the brake rods of the vehicle, to set the brakes. The braking mechanism of the present invention operates in conjunction with such a service braking system, and, as mentioned above, serves to set and latch the brakes of the vehicle whenever the air pressure in the service braking system falls below a predetermined threshold.
Accordingly, a primary objective of the present invention is to provide an emergency and parking braking mechanism which is particularly adapted for use in conjunction with motor vehicles of the type using air brakes which necessitates a source of air under pressure for their operation, the braking mechanism of the invention being adapted to set and latch the brakes of the vehicle at any time that there is insufficient pressure from the source.
Another objective of the present invention is to provide an improved braking mechanism which is adapted to set and latch the brakes of the vehicle whenever the service braking system is in an abnormal condition, the mechanism of the invention incorporating a minimum number of parts so that it is not only subject to simple and trouble-free operation, but it also lends itself to economical mass production.
Another object of the present invention is to provide such a braking system which serves to operate air-operated brakes under emergency conditions, as when the air line is broken, or is leaking; and which when desired, may also serve as a parking brake.
Another objective of the invention is to provide such an emergency and parking brake mechanism which applies a mechanical lock to the brakes when set, which is not dependent on a compressed air source, which could be subject to leakage, and which has no tendency to fail when it has been set.
Yet another objective of the invention is to provide such an improved emergency and parking brake mechanism which may be mechanically released (for example, by a special tool to prevent vandalism), should it become necessary to move a parked trailer, or the like, when no source of compressed air is available.